Worse than at least 18 diesel cars

Reducing fine particulate pollution from diesel vehicles has been the focus of many efforts to clean up our air. Emissions standards for diesel vehicles have been tightening up over the years.

However, according to a recent article about London, England, any improvements in that city’s air arising from stricter diesel standards have been negated by the increased use of wood heat.

Wood stoves, it turns out, emit many more fine particulates than most diesel vehicles.

In 2017,  the Air Quality Expert Group in the UK, released a report, “The Potential Air Quality Impacts from Biomass Combustion“, which compared factory rated emissions from various years of diesel cars and Heavy Goods Vehicles to factory rated emissions from wood stoves.

What they found is that even a new eco-design stove, rated at 3.1 grams/hour of fine particulate emissions, puts out more fine particulate pollution per hour than 18 diesel cars that have been made since 2014.

Emissions uncertainty greater with wood

And while the authors noted that emissions from either a stove or a car can vary a lot from its factory rating, as much depends on how it is operated and maintained, they highlighted there was much greater uncertainty when it came to the use of wood stoves.

The report highlights results from a study of wood stove emissions in New Zealand:

“The results suggested that real world emissions may be up to 4-5 times those achieved within legislated test cycles and laboratory “real world” studies. Even burners with authorisation particulate test emissions below 1.5 g/kg, could achieve real world emissions factors of up to 13.0 g/kg.” (p. 28)

So when you see smoke coming from a chimney, remember that it is putting out at least 18 times as much fine particulate matter per hour than a newer diesel car (if you actually can see the smoke, it is guaranteed to be putting out far more than just 18 diesel cars worth, every hour).

Would you want a fleet of diesel cars idling every winter evening, for hours on end, next to your home?